Laboratory process specifications for assuring quality in the U.S. National Cholesterol Education Program

Area of Science:

• Clinical Chemistry
• Laboratory Quality Assurance
• Medical Diagnostics

Background:

• The U.S. National Cholesterol Education Program (NCEP) provides guidelines for cholesterol testing quality.
• Ensuring the accuracy of cholesterol tests is crucial for proper medical interpretation and patient care.
• Laboratory testing involves pre-analytical and analytical variables that can impact test results.

Purpose of the Study:

• To assess laboratory specifications for cholesterol testing quality aligned with NCEP guidelines.
• To develop a model relating NCEP interpretation guidelines to pre-analytical and analytical variables.
• To derive allowable imprecision (CV) and inaccuracy (bias) specifications and necessary quality-control procedures.

Main Methods:

• Developed a model to connect NCEP cholesterol test interpretation guidelines with influencing variables.
• Derived specifications for allowable imprecision (CV) and bias under stable operation.
• Determined quality-control procedures (rules, control measurements) for detecting unstable operation.

Main Results:

• NCEP goals (CV ≤ 3%, bias ≤ ±3%) are inadequate for single cholesterol tests with common quality-control procedures.
• With two control measurements, 3% CV is only acceptable with zero bias; 2% CV is needed for ±3% bias.
• With four control measurements, 3% CV is acceptable for ±1.5% bias; 2.5% CV is required for ±3% bias.
• NCEP 3% goals are adequate for two serial tests with four control measurements per run.

Conclusions:

• Current NCEP quality goals for cholesterol testing are insufficient for ensuring the reliability of individual results.
• Tighter laboratory imprecision and bias specifications are necessary, especially when using fewer control measurements.
• Optimized quality-control procedures are essential for detecting analytical instability in cholesterol testing.